Chemokinetic assay
After serum starvation for 18 h, Pkd2+/+ or Pkd2−/− MEFs (5×104/insert) were seeded in inserts (8 μm in pore size, BD Biosciences), which were placed in 24-well dish containing 500 μl of media supplemented with 0.1% FBS and PBS, WNT9B (1 μg/ml) or PDGF-BB (25 ng/ml). Cells were allowed to migrate through inserts for 6 h at 37°C. Cells in the lower side of inserts facing the bottom of the well were fixed with methanol, stained with hematoxylin and eosin, and counted. Quantification of migrating Pkd2+/+ or Pkd2−/− cells was obtained from 3 independent experiments done in sextuplicates (WNT9B) or quadruplicates (PDGF-BB).